instmctions); The Animal, Cell and Tissue Culture Core (Core B) will be responsible for providing investigators of the Program Project (PPG) with animal models, tissues and cells necessary to achieve their specific aims. Experiments of this PPG focus on identifying mechanisms responsible for differences in longevity between the species of rodents. Rodents offer a unique opportunity for such comparative study of longevity because of over 10-fold differences in life spans represented within a single mammalian order. For example, short- lived rodents, such as mouse and rat, live 3-5 years, while long-lived rodents, such as naked mole rat, blind mole rat, grey squirrel, beaver, and porcupine have maximum lifespans ranging from 21 to 32 years. To enable the study of molecular mechanisms of longevity in these animals, it is essential to provide access to biological materials from several individuals of multiple rodent species. Core B will maintain and replenish, as needed, the collection of tissues and primary cells from 18 species of rodents. The Core will provide project investigators with tissues, cells, DNA, and RNA, and perform mutagenic treatments of cells. In addition. Core B will maintain mice and naked mole rats for the use by project investigators. Considering the effort needed to collect and establish cell cultures from non-standard organisms that are not commercially available, the centralized resource will save time and effort, and reduce costs! Maintaining the centralized rodent collection will also standardize culture conditions, quality control and biological samples for use across PPG projects, improve reproducibility of results and allow the analysis of the same individual animals by several assays and projects, as well as minimize animal use. RELEVANCE (See instructions); The Animal, Cell and Tissue Culture Core (Core B) will maintain animal, cell and tissue collection for the project investigators. This resource is essential for all the four projects to achieve their specific aims.